Dovetail joint fit need help with correction

[Beau J]

i will do so today. you suggest the book on martin style guitars correct? or the one for several different kits

[ken cierp]

Martin Style kits

[ken cierp]

Beau, I have to apologize for making some assumptions, first I thought you had purchased Bill Cory’s Book which I recommended early on in this process. It contains the necessary sanding tool design and information for properly sanding the tenon. Most importantly, the cause and effect elements of material removal are explained. Second I assumed that you understood that this

"Your goal right now should be getting the neck plane and the finger board extension area to form a straight line

Clamp the level to the neck or use a piece of flat MDF"

was not an option but rather a requirement to prevent exactly what has now occurred --- over sanding the angle and tipping the neck back too far.

Tim and others may have different advice, but if I were you I would purchase a “B” quality Martin neck off Ebay and start over. This time armed with Bill’s book and a better understanding of what’s required.

[Tim Benware]

I wouldn't give up quite yet, I've been there and it may not be that far off. Early on I did the exact same thing and the effort to correct it went a long way toward improving my knowledge and skill of the DT joint and realizing how I might improve my technique and the simplicity of the M&T in comparison.

You probably still have room to correct the angle back in the other direction but what you may find as you continue to work it, is the tenon MAY need to be trimmed back as it will get deeper into the mortise and as that happens the fret board now needs to sit in a different location because you are sanding back the top portion of the heel now. The 14th fret location moves forward on top of the neck. On one I did I had to file an angle on the nut bottom (like the old Martin ones) because it now was on the headstock angle.

These may help:

1. Mark your heel as in the pic, you will be angling back in the opposite direction from before so now you don't want to take off any at the bottom (before it was the top)
2. Make a sanding block as shown, it is 5" x 3/4" x 3/4", the bevel will help get in where you need and hold easier. Use 100 or 120 grit so you don't get to aggressive.
3. From the TOP of the heel, sand 5 strokes from the top to the 1, then 5 strokes from the top to 2, then 5 strokes from the top to 3, then 5 strokes from the top to 4. Do the same to the opposite side and then check you results. You'll find that this will be a total of 20 strokes from top to 1, 15 from top to 2, 10 from top to 3, 5 from top to 4 and none from 4 to the bottom. YOU MUST KEEP THE SANDING BLOCK PARALLEL TO THE HEEL LINE. It helps to cut a relief around the tenon so you are only sanding the portion of the cheek that is going to be in contact with the body.

I can tell you from first hand experience this can be as frustrating as hell. It's not easy at first but gets better with experience. I have put a DT neck off to the side and got a new one like Ken suggested and then come back to it years later and corrected the problem as I have stated above. You're looking at one in the photo.

[TonyinNYC]

Tim,
I don't use dovetails, but I have had to adjust the neck angle on my builds. The sanding method you describe is, in my opinion, so much better than what I have been doing! I just floss the neck joint now. It takes a long time to adjust the angle this way. I am going to give your method a shot on the next one. I think I will be much happier.
Thanks!
Tony

[Tim Benware]

Tim,
I don't use dovetails, but I have had to adjust the neck angle on my builds. The sanding method you describe is, in my opinion, so much better than what I have been doing! I just floss the neck joint now. It takes a long time to adjust the angle this way. I am going to give your method a shot on the next one. I think I will be much happier.
Thanks!
Tony

YW, the key is keeping the sanding block flat and parallel to the work without "rolling" it from side to side or off the bottom of the heel. As you know, flossing presses the two surfaces together to match shapes. When I get the angle real close I floss to fine tune it.

[ken cierp]

Assuming (I need to take care with that assuming stuff) that the finger-board is not attached ---- flossing to mate the surfaces is done by pulling the abrasive out to the side. To tilt the neck plane back away from the sound board pull the abrasive toward the back. To tilt the neck plane up toward the sound board, pull the abrasive toward the top. Its a matter of the sand paper being in contact with the wood longer in the direction it is being moved. --- Make sense?